Embedded hardware: electronic components (1) resistance capacitance inductance

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One . resistor

1. The meaning of resistor ： In a circuit, there is Block the action and cause energy consumption The part of is called resistance .

2. The abbreviation of resistor ：R（Resistor） And resistance elimination RN

3. Resistor in circuit symbol ：

4. A common unit of a resistor ： Kiloohm （KΩ）, Megaohms （MΩ）

5. Unit conversion of resistors ：1 Mega ohm = 10³ Thousand euro = 10⁶ o

6. Characteristics of resistors ： The resistance is a linear element , That is, the voltage at both ends of the resistance is proportional to the current flowing through the resistance , The intensity of the current passing through the conductor is inversely proportional to the resistance of the conductor . Ohm's law ：I=U/R.

7. The function of the resistance is to shunt 、 Current limiting 、 partial pressure 、 bias 、 wave filtering （ Used in combination with capacitors ） And impedance matching .

8. Resistors are used in circuits “R” Add numbers to indicate , Such as ：R15 Indicates that the number is 15 The resistor .

9. The methods for marking the parameters of resistors in circuits are 3 Kind of , Direct calibration method 、 Color and number .

• a) The direct labeling method The nominal value of the resistor is directly marked on the resistor body with numbers and characters , The allowable deviation is expressed as a percentage , If the deviation value is not marked, it means ±20%;

• b) Digital notation It is mainly used for small size circuits such as chip mounting , In three digit numbers , First from left to right , Two digits represent significant digits , The third means 10 Or use R Express (R Express 0.);

  Such as ：472 Express 47×10²Ω（ namely 4.7KΩ);

  ​ 104 be 10x10⁴ Express 100KΩ;

  ​ R22 Express 0.22Ω;

  ​ 122=1200Ω=1.2KΩ;

  ​ 1402=14000Ω=14KΩ;

  ​ 50C=324*100=32.4KΩ( Look up the table ：50 Representation number 324、C Express 10 Of 2 Power );

  ​ 17R8=17.8Ω;

  ​ 000=0Ω;0=0Ω.

• c) Color ring notation Most used , For ordinary color ring resistors 4 Ring representation , For precision resistors 5 Ring representation , The color ring close to one end of the resistor is the first ring , The other end with more exposed resistance is the end ring . Here is an example ：

  If the color ring resistor is represented by four rings , The first two digits are significant digits , The third is 10 Power of , The fourth ring is the error range of the color ring resistor ( See the picture below )

If the color ring resistor is represented by five rings , The first three digits are significant digits , The fourth is 10 Power of . The fifth ring is the error range of the color ring resistor .

• d) SMT Representation of precision resistors ： It is usually used 3 Bit mark . It's usually 2 Digit numbers and 1 Bit letters indicate , Two numbers are significant numbers , Letters mean 10 Power of , But you should look it up in the precision resistance query table according to the actual situation . The following is a query table of precision resistors ：

Such as looking up the table ：50 Representation number 324、C Express 10 Of 2 Power ,50C=324x100=32.4KΩ

10. SMT The dimension of the resistance indicates ： In terms of length and width （ Such as 0201,0603,0805,1206 etc. , Specific as 02 It's long for 0.02 Inch ,01 Indicates that the width is 0.01 Inch ）.

11. Generally, there are two ways to connect the resistance in the circuit ： Series connection and parallel connection

Calculation of resistance ：

Series connection ：R=R1+R2 parallel connection ：R=1/R1+1/R2

12. Calculation method of series and parallel connection of multiple resistors ：

Series connection ：R Total string =R1+R2+R3+……Rn

parallel connection ：1/R Always combine =1/R+2/R+3/R……1/Rn

13. Detection of good and bad resistors ：

• a） use Pointer multimeter Judge whether the resistance is good or bad ： First select the measuring gear , Then set the magnification knob to the appropriate gear , commonly 100 Resistors below ohms are optional RX1 files ,100 ohm -1K Ohm resistors are optional RX10 files ,1K ohm -10K Ohmic resistors are optional RX100 files ,10K-100K Ohm resistors are optional RX1K files ,100K Resistors above ohms are optional RX10K files ;
• b） After the measurement gear selection is confirmed , Calibrate the resistance gear of the multimeter 0, school 0 Approach is to ： Short circuit the two probes of the multimeter to the metal bar , Observe whether the pointer reaches 0 The location of , If not 0 Location , Adjust the zero adjustment knob to point to the resistance scale 0 Location ;
• c） Then connect the two leads of the multimeter to the two ends of the resistor respectively , The gauge needle should be on the corresponding resistance scale , If the needle does not move and the indication is unstable, or the indicated value differs greatly from the indicated value on the resistor , The resistor is damaged .
• d） use Digital multimeter Judge whether the resistance is good or bad ： First, adjust the gear knob of the multimeter to the appropriate gear of ohm , commonly 200 Resistors below ohms are optional 200 files ,200-2K Ohmic resistors are optional 2K files ,2K-20K Ohms optional 20K files ,20K-200K Ohm resistors are optional 200K files ,200K-200M Ohm resistor selection 2M Ohmic gear ,2M-20M Ohm resistor selection 20M files ,20M Resistor selection above ohms 200M files .

Two . Capacitor

1. The meaning of capacitor ： A physical quantity that measures the ability of a conductor to store electric charges .

2. The abbreviation of capacitor ：C (capacitor) or CN（ Drainage ）

3. The representation of a capacitor in a circuit ：

4. A common unit of a capacitor ： Millisecond （mF）、 Micro method （uF）、 NAFA （nF）、 Pefa （pF）

5. Unit conversion of capacitor ：

1 Farah =10³ Millisecond =10⁶ Micro method =10⁹ NAFA =10¹² Pefa ; 1pf=10^-3nf=10^-6uf=10^-9mf=10^-12f

6. The function of capacitance ： Isolated DC , bypass , coupling , wave filtering , compensate , Charge and discharge , Energy storage etc.

7. Characteristics of capacitors :： The capacity of the capacitor is Indicates the amount of electrical energy that can be stored , The blocking effect of capacitance on AC signal is called Capacitive reactance , It is related to the frequency and capacitance of AC signal . The characteristics of capacitance are mainly Direct communication , Turn on low-frequency resistance and high-frequency resistance .

8. Capacitors are generally used in circuits “C” Add numbers to indicate , Such as C25 Indicates that the number is 25 The capacitance of .

9. The identification method of capacitor is basically the same as that of resistance , The method of dividing and direct marking 、 Color and number 3 Kind of .

• a) The direct calibration method is to express the nominal value of the capacitance in numbers and units on the body of the capacitance ： Such as ：220MF Express 220UF;.01UF Express 0.01UF;R56UF Express 0.56UF;6n8 Express 6800PF;

• b) A numerical representation of non-standard units ： One to four digits are used to represent significant digits , It's usually PF, The capacity of the electrolytic capacitor is UF. Such as :3 Express 3PF;2200 Express 2200PF;0.056 Express 0.056UF;

• c) Digital representation ： Generally, three numbers are used to indicate the capacity , The first two digits are significant numbers , The third means 10 Power of . Such as 102 Express 10x10²=1000PF;224 Express 22x10⁴=0.2UF

• d) Use color ring or color dot to represent the main parameters of capacitor . The color coding method of capacitor is the same as that of resistance .
  Capacitor deviation symbol ：+100%-0–H、+100%-10%–R、+50%-10%–T、+30%-10%–Q、+50%-20%–S、+80%-20%–Z.

10. Classification of capacitors ： According to the polarity, it can be divided into polar capacitance and nonpolar capacitance , We often see electrolytic capacitors with polarity , There are positive and negative poles .

11. The main performance index of the capacitor is ： Of capacitors Capacity ( That is, the capacity to store electric charge ), Withstand voltage value ( It refers to the effective value of the maximum DC voltage or the maximum AC voltage that the capacitor can work reliably for a long time within the rated temperature range ), Temperature resistance value ( Indicates the maximum operating temperature that the capacitor can withstand ).

12. The brands of capacitors are ： Mainboard capacitors are mainly divided into Taiwan series and Japanese series , Japanese brands have ：NICHICON,RUBICON,RUBYCON（ Ruby ）、KZG、SANYO（ Sanyo ）、PANASONIC（ panasonic ）、NIPPON、FUJITSU（ Fujitsu ） etc. ; Taiwan brands have ：TAICON、G-LUXCON、TEAPO、CAPXON、OST、GSC、RLS etc. .

13. Calculation of capacitor ：

​ 1/C=1/C1+1/C2 C=C1+C2

Calculation formulas for series and parallel connection of multiple capacitors ：

C strand ： 1/C=1/C1+1/C2+1/C3+…+1/CN

C and ： C=C1+C2+C3+……+CN

14. Measurement of the quality of capacitors

• a) Detect when leaving the line

  Use a multimeter Ｒ×１ｋ block , Before testing , First, touch the two pins of the electrolytic capacitor , So as to discharge the residual charge in the capacitor . When the probe is just turned on , The needle is deflected to the right by an angle , Then the needle slowly turns to the left , At last the needle stopped . The resistance indicated by the meter needle when it stops is the leakage resistance of the capacitor , The greater the resistance, the better , It is best to approach infinity . If the leakage resistance is only tens of kiloohms , This indicates that the electrolytic capacitor has serious leakage . The more the needle swings to the right （ The needle should also swing back to the left ）, It shows that the capacitance of this electrolytic capacitor is also larger , On the contrary, the smaller the capacity .

• b) Direct detection on the line

  It mainly detects whether the capacitor has been open circuit or broken down , However, the leakage fault is usually uncertain due to the influence of external circuit . With a multimeter Ｒ×１ block , After the circuit is disconnected , First discharge the remaining charge in the capacitor . When measuring, if the needle deflects to the right , Description: the electrolytic capacitor has an internal open circuit . If the resistance indicated by the meter needle is very small after it is deflected to the right （ Near short circuit ）, It indicates that the capacitor has serious leakage or has been broken down . If there is no rotation after the needle deviates to the right , But the indicated resistance is not very small , It indicates that the possibility of open circuit of capacitor is very high , It shall be further tested after disconnecting the circuit .

• c) Detect when the line is powered on

  If it is suspected that the electrolytic capacitor has a breakdown fault only when it is energized , The circuit can be energized , Then measure the DC voltage at both ends of the capacitor with the DC gear of the multimeter , If the voltage is very low or ０Ｖ, The capacitor has been broken down . For positive of electrolytic capacitor 、 The negative pole is not clearly marked , We must first identify its positive 、 Negative pole . Test twice with the multimeter , The leakage is large （ The resistance value is small ） One time shall prevail , The black probe is connected to a negative pole , The other leg is the positive pole .

3、 ... and . Inductor

1. The English abbreviation of inductor ：L (Inductance) Circuit symbol ：

2. The international standard unit for inductors is ：H( Henry ) mH( Milliheng ) uH（ Weiheng ）nH（ Nahen ）

3. The unit conversion of inductors is : 1 H=10³ mH＝10⁶ uH＝10⁹ nH;1 nH＝10^-3 uH=10^-6 mH=10^-9 H

4. Characteristics of inductors ： Connect DC and isolate AC ; Turn on low-frequency resistance and high-frequency resistance .

5. The role of the inductor ： wave filtering , Trap wave , Oscillate , Store magnetic energy, etc .

6. Classification of inductors ： Hollow core inductance and magnetic core inductance , Core inductance can also be called iron core inductance and copper core inductance . Copper core wound inductors are common in the motherboard .

7. Inductance is commonly used in circuits “L” Add numbers to indicate , Such as ：L6 Indicates that the number is 6 The inductance of . The inductance coil is made by winding the insulated wire on the insulating frame for a certain number of turns . Direct current can pass through the coil , The DC resistance is the resistance of the wire itself , The pressure drop is very small ; When the AC signal passes through the coil , Self induced electromotive force will be generated at both ends of the coil , The direction of the self induced electromotive force is opposite to that of the applied voltage , Block the passage of communication , So the characteristic of the inductor is through DC resistance AC , The higher the frequency is. , The greater the coil impedance . Inductance and capacitance in the circuit can form an oscillation circuit . Inductance generally has direct mark method and color mark method , Color coding is similar to resistance . Such as ： Brown 、 black 、 gold 、 Golden expression 1uH（ error 5%） The inductance of .

8. Measurement of inductance ： The quality inspection of inductance includes appearance and resistance measurement , First, check whether the appearance of the inductor is intact , Whether there is magnetic defect 、 crack 、 Whether the metal part has corrosion and oxidation , Whether the signs are complete and clear , Whether the wiring is broken or damaged . Use a multimeter to make a preliminary test on the inductance , Measure the DC resistance of the coil , And compare with the known normal resistance value . If the detected value is significantly higher than the normal value , Or the pointer doesn't move , It may be that the inductor body is open . If it is much smaller than the normal value , It can be judged that the inductor body is seriously short circuited , Local short circuit of coil shall be detected by special instrument .